Our studies for 1975-1976 will focus on two areas: (1) Animal studies: Effect of increased stimulation on DNA and protein synthesis in the rat parotid gland and in parotid saliva, (2) Human studies: a) Characterization of the "Acidic Protein-Kallikrein" relationship in human parotid saliva and b) Distribution of parotid "acidic proteins" in health and disease. With increased mastication (enhanced secretion) due to increased food intake, there are increases in gland weight, rate of protein synthesis, RNA and amylase content and total gland DNA. It is known that gland stimulation by isoproterenol (which also enhances secretion) results in an increase in DNA content of the gland. Recently it has been shown that the proteins isolated from parotid saliva of animals who have received isoproterenol for 7 days have very different acrylamide gel electrophoretic patterns. We will quantitate the mitotic rate for the parotid gland of animals with increased food intake and will relate this to gland DNA content. We will examine parotid saliva acrylamide gel electrophoretic patterns for changes in banding and will determine the specific activities of known salivary proteins in the saliva of these animals and will compare them to control animals maintained on regular chow. We have isolated an acidic proline-rich vasoactive protein from human parotid saliva, which exhibits a single band on acrylamide gel electrophoresis and has biochemical properties similar to those of proline-rich proteins isolated by Oppenheim, et al. and Bennick and Connel. However, it also exhibits properties similar to human salivary kallikrein, although its amino acid composition does not resemble that of kallikrein. We will further characterize this protein and will attempt to demonstrate whether or not our protein acts as a carrier protein as has been reported for other acidic proteins which are rich in proline, glutamic and aspartic acids. We also plan to observe the distribution of the parotid acidic proteins in a variety of functional and disease states.